Mouthguard



FIG. 1 is a front perspective view of the ornamental design for a mouthguard;

FIG. 2 is a front view thereof;

FIG. 3 is a front cross-sectional view thereof, taken at line 3-3 of FIG. 6;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a left view thereof;

FIG. 7 is a right view thereof; and,

FIG. 8 is a bottom view thereof. 

CLAIM The ornamental design for a mouthguard, as shown and described. 